Ribosomal fractions obtained from sand ground cell of Bordetella pertussis are a good protective immunogen in mice. This cell fraction contains only about 20-40 proteins, as compared to several hundreds of proteins in whole cells. Using the ribosomal fraction as an enriched starting material, attempts to identify and purify protective antigens will be made. The most effective purified vaccine and a standard whole cell vaccine will be used to study immunity to pertussis in mice and marmosets. By evaluating the role of antibody and of immune cells, information relevant to pathogenesis may be obtained. Furthermore, the careful evaluation of the type of protection conferred by conventional vaccine is of great importance since knowledge in this area is scanty. Whether ribosomal vaccines are practical for large scale administration to humans is unresolved. However, an understanding of the basis of immunity to pertussis confirmed by pure substances is highly desirable. This information would allow rational planning of an improved pertussis vaccine.